Is a two-pool MT model valid in tissues with multicomponent T2?

Portnoy S, Stanisz G

University of Toronto

Quantitative MT analysis is usually performed using the Two-Pool Model of MT exchange. However, this model does not account for the multiple liquid T2 components that occur in tissues. Thus, the physical interpretation of liquid pool T2 estimates extracted from Two-Pool Model fits to MT data has remained uncertain. By comparing MT and T2 decay data in white matter, this study demonstrates that T2 measured from MT experiments is equal to the inverse of a tissues mean transverse relaxation rate. This finding suggests that on the time scale of typical MT experiments, the multiple liquid T2 components are indistinguishable, validating the use of a Two-Pool Model description for steady state MT data.